This invention relates to improvements in an external metering valve for use with a fuel cell, aerosol can, or dispenser for dispensable fluid.
As exemplified in Nikolich U.S. Pat. Nos. 4,403,722, 4,483,474, 4,522, 162, and 5,115,944, all of which are incorporated by reference, it is known to use a dispenser for a dispensable fluid to dispense a hydrocarbon fuel to a combustion gas-powered tool, such as, for example, a combustion gas-powered fastener-driving tool. Such fastener-driving tools and such fuel cells are available commercially from ITW-Paslode (a division of Illinois Tool Works, Inc.) of Vernon Hills, Ill., under its IMPULSE trademark. In particular, a suitable fuel cell is described in Nikolich U.S. Pat. No. 5,115,944, listed above.
Two systems are known for attaching an external valve to a fuel cell of this type. In the first known system, the valve is fully engaged with the fuel cell (See FIG. 1). In the second known system, the valve is positioned in a holding or shipping cap on the top of the fuel cell in a disengaged position (See FIG. 2). To place the fuel cell in operation, the user must remove the shipping cap and depress the valve into the engaged position depicted in FIG. 1.
The first system is known to be "friendly" to the user, since it is completely ready for use. However, at the same time, this system exposes the valve to the contained fuel for the whole life of the unit, from the moment it is manufactured until the fuel is completely used up. This shortens the useful life of the fuel cell due to product leaks, not only from the internal seals in the fuel cell, but also through seals located in the valve.
A significant drawback of the second system is not additional leaks, but its complexity to the user. The user must be warned to remove the shipping cap and properly install the valve in a two-step process, otherwise the system will not work or may expel some product from the fuel cell. Also, trying to install the fuel cell with the shipping cap still in place can cause extensive damage to the tool.
Accordingly, one object of the present invention is to provide an improved external valve for a fuel cell that can be engaged with the fuel cell in a shipping position without the need for a shipping cap so that unwanted fuel emission is prevented.
Another object of the present invention is to provide an improved external valve for a fuel cell that is readily moved from the shipping position to an operational position in which the valve is in fluid communication with the fuel cell.
Yet another object of the present invention is to provide an improved external valve for a fuel cell which has a shipping position and is placed in an operational position upon installation in the tool.